Pool water heater

ABSTRACT

An electric heater for heating pool water includes an enclosure, a pool water inlet and outlet, a heat exchanger disposed within the enclosure and comprising a plurality of metal pipes coupled to the pool water inlet and outlet, an electric heating element disposed within the enclosure and spaced apart from the plurality of metal pipes, and a conduit coupled between the plurality of metal pipes and the pool water outlet.

TECHNICAL FIELD

This specification generally relates to heating pool water.

BACKGROUND

Swimming pools have traditionally been heated using gas fired heaters.Gas fired heaters generally have a low efficiency rate, because a greatamount of heat is lost to the environment. Therefore, the cost ofheating pool water using gas heaters is expensive. An alternative to agas heater is an electric pool heater, such as a heat pump. A heat pumptakes warm air from the atmosphere and forces it through coils thattransfer the heat to the pool water. Although more efficient thantraditional gas heaters, heat pumps take a long period of time to heatup a large body of water. A second alternative to a gas heater is anelectric heater that uses a heating element. These electric heaters tendto be more efficient than heat pumps because the heating element is indirect contact with the body of water. Although these electric heatersare more efficient, the size of the electric element needed to heat alarge body of water makes this method of pool heating very expensive andimpractical.

SUMMARY

In a general aspect, an electric heater for heating pool water includesan enclosure, a pool water inlet and a pool water outlet, a heatexchanger within the enclosure and including a plurality of metal pipescoupled to the pool water inlet and outlet, an electric heating elementdisposed within the enclosure and spaced apart from the plurality ofmetal pipes and a conduit coupled between the plurality of metal pipesand the pool water outlet.

Implementations of this aspect may include one or more of the followingfeatures. For example, the heat exchanger includes 20 to 25 metal pipes.For example, each of the plurality of metal pipes is copper pipes. Forexample, the electric heater further includes a thermal sensor tomeasure the internal temperature of the enclosure. For example, theenclosure includes a first insulated portion coupled to a secondinsulated portion.

Implementations may include one or more of the following aspects. Forexample, the electric heater further includes a first header and asecond header, where the first header is in fluid communication with thepool water inlet and a first end of each of the plurality of metal pipesand the second header is in fluid communication with a second end ofeach of the plurality of metal pipes and the conduit.

Implementations may include one or more of the following aspects. Forexample the temperature-dependent flow thermostat is set to permit flowof heated pool water to the pool when the pool water heated by theexchanger reaches a temperature of about 125° F.

Implementations may include one or more of the following aspects. Forexample, the pool water inlet and the pool water outlet are in fluidcommunication with a bypass valve. For example, each of the plurality ofmetal pipes is the same length and is evenly spaced from each other. Forexample, each of the plurality of metal pipes has a diameter of about0.5 to about 1 inch. For example, the electric heater further includes acondensation pan disposed within the enclosure.

In a general aspect, a method for heating pool water includes receivingpool water through an inlet of an electric pool water heater. The methodincludes flowing a portion of the pool water through a plurality ofmetal pipes spaced apart from an electric heating element. The methodincludes intermixing the portion of the pool water that has flowedthrough the plurality of metal pipes with a portion of the pool waterflowing through a bypass valve. The method includes flowing theintermixed portions of pool water through an outlet of the electric poolwater heater to the pool.

Implementations may include one or more of the following aspects. Forexample, the portion of the pool water that flows through the pluralityof metal pipes is heated to a set temperature. For example, the poolwater that flows through the plurality of metal pipes is heated to 125°F. For example, a temperature dependent thermostat is opened to allowthe portion of the water that is flowed through the plurality of metalpipes to intermix with the portion of water that flows through thebypass valve when the water in the plurality of metal pipes is at theset temperature. For example, flowing a portion of the pool waterthrough a plurality of metal pipes, including, receiving, by a firstheader, a portion of the pool water from the inlet and distributing, bythe first header, the portion of the pool water to a first end of eachof the plurality of metal pipes. For example, the portion of pool waterfrom the inlet that is received by the first header is below a settemperature. For example, the plurality of metal pipes includes 20 to 25pipes and the pipes have a diameter of about 0.5 to about 1 inch.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features,objects, and advantages will be apparent from the description anddrawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a top view of an electric heater for heating pool water.

FIG. 2 is a side view of the electric heater of FIG. 1.

FIG. 3 is a side view of a front header of the electric heater of FIG.1.

FIG. 4 is a side view of a housing unit for the electric heater of FIG.1.

DETAILED DESCRIPTION

The present invention is directed to an electric heater for heating poolwater. The electric heater receives pool water and flows the pool waterthrough a heat exchanger that is heated by an electric heating element.The heated pool water that exits the heat exchanger is intermixed withpool water that has bypassed the heater and the intermixed water isreturned to the pool.

As illustrated in FIG. 1, the electric pool heater 100 includes a poolwater inlet 110, a pool water outlet 112, a front header 120, a heatexchanger 122, an electric heating element 124, a rear header 126, eachof which are enclosed, partially or wholly, within an enclosure 136. Aheat exchanger bypass valve 114 and a pool water thermistor 116 arepositioned between the pool water inlet 110 and pool water outlet 112. Aconduit 128 connects the rear header 126 to the front header 120 andpool water outlet 112 via an elbow 134. The pool heater 100 furtherincludes a heated water thermostat 130, high temperature limitswitch(es) 132, and a heat box thermistor 138, each of which will bedescribed in more detail below.

The electric pool heater 100 and its constituent components can beenclosed (partially or wholly) within a housing unit 142. In someimplementations, the housing unit 142 may be formed of two complimentaryhalf sections that are joined together. In some examples, the housingunit 142 may be insulated. The pool water inlet 110 and pool wateroutlet 112 are connected to the body of water in the pool by pipes (notillustrated) and pipe unions 144. The pool water inlet 110 introduceswater from the pool into the heater 100. A flow switch 118 is mounted onthe pool water inlet 110 and monitors the flow of pool water into thepool water inlet 110. The flow switch 118 also acts as a safety deviceby ensuring that the heater 100 does not operate, for example, if thereis no flow of pool water to the heater 100. The pool water outlet 112transports water from the heater 100 back to the pool. The pool wateroutlet 112 is connected to a pipe that returns the heated water to thepool.

The pool water inlet 110 and the pool water outlet 112 are in fluidcommunication with a heat exchanger bypass valve 114. The heat exchangerbypass valve 114 may be a spring loaded valve that allows some or all ofthe pool water introduced into the pool water inlet 110 to return to thepool via the pool water outlet 112. For example, when there is no heatedwater returning from the heat exchanger, the pressure of the pool waterflowing into pool water inlet 110 is high enough to cause the bypassvalve 114 to open thereby allowing a large proportion if not a majorityof the pool water to bypass the heater 100 and flow back to the pool.When, however, the pool water temperature falls below a desiredtemperature by an amount usually set by the heater installer or user,the pool water flows through the heat exchanger and is heated by theheater thereby causing a pressure differential by the water flowingthrough the pool water outlet 112 as compared to the pool water inlet110, thereby causing the valve 114 to close such that only a portion ofpool water bypasses the heat exchanger.

The pool water thermistor 116 is coupled to the pool water inlet 110,and measures the temperature of the pool water received by the poolwater inlet 110. The front header 120 is in fluid communication with thepool water inlet 110 and the heat exchanger 122. The heat exchanger 122includes a plurality of metal pipes or tubes. The heat exchanger 122receives a portion of the pool water that enters the pool water inlet110. The front header 120 distributes the portion of the pool water thatis received by the heat exchanger 122 to the plurality of metal pipes ortubes. The plurality of metal pipes or tubes may be composed of avariety of different metals. In some examples, the heat exchanger 122comprises 20 to 25 metal pipes or tubes. In these examples, theplurality of metal pipes may have the same length and may be spacedevenly apart from each other. For example, the plurality of metal pipescan be about 2 feet in length and spaced about 1 inch apart from eachother. In one implementation, each of the plurality of metal pipes ismade from copper. Other metals may also be used, such as copper alloys(e.g., copper-nickel alloy), titanium, and stainless steel. In someother examples, the diameter of each of the plurality of metal pipes ortubes is about 0.5 and 1.0 inch, for example 0.75 inches.

As shown in FIG. 1, the heat exchanger 122 is disposed within theenclosure 136. The enclosure 136 is insulated by one or more layers ofinsulating material 146. In some examples the enclosure is a metal heatbox, for example an aluminum box. The heat box thermistor 138 is mountedto the inner wall of the enclosure 136. The thermistor 138 measures theambient temperature within the enclosure 136. In some implementations,the enclosure 136 can be formed of two complimentary parts coupledtogether. The first part of the enclosure 136 can be removed to exposethe plurality of metal pipes within the heat exchanger 122. FIG. 1 is atop view of the electric heater 100 with the top part of the enclosure136 removed. The two parts of the enclosure 136 can be coupled togetherusing a plurality of fastener mechanisms 134. For example, glue tabs andrivets can be used, either individually or in combination, to fasten thetwo complimentary parts of the enclosure 136 together. In otherimplementations, screws, bolts, or other fasteners may be used inconjunction with adhesive materials, but adhesives are not required. Asillustrated in FIG. 1, when the top part of the enclosure 136 is open,the plurality of metal pipes of the heat exchanger 122 and the electricheating element 124 are exposed such that, for example, a user canaccess the internal components for maintenance, cleaning, or the like.

The electric heating element 124 is also disposed within the enclosure136. The electric heating element 124 can be spaced apart from theplurality of metal pipes of the heat exchanger 122 such that theelectric heating element 124 does not come into contact with the poolwater. As illustrated in FIG. 1, the heating element 124 can be a singleheating element that extends the length of the enclosure 136. In someexamples, the heating element 124 can be twisted in a coil arrangement.The heating element 124 can have a power rating of about 800 watts. Theheating element 124 can be a metal heating element or a ceramic heatingelement. Although not shown in FIG. 1, the heating element 124 isconnected to a power source.

The rear header 126 is coupled in fluid communication with the end ofeach of the plurality of metal pipes of the heat exchanger 122 and theconduit 128. The rear header 126 receives heated pool water from theplurality of metal pipes of the heat exchanger 122. The rear header 126receives the heated pool water from the plurality of metal pipes of theheat exchanger 122 and converges the heated pool water into the conduit128 via elbow 134. The heated water thermostat 130 is coupled to therear header 126 and measures the temperature of the heated water thatexits the heat exchanger 122. In one implementation, there are two highlimit switches 132, one located in the elbow 134 and the other locatedin the rear header 126. In another implementation, a single high limitswitch 132 may be mounted in either the elbow 134 or the rear header126. Although not illustrated in FIG. 1, the high limit switch(es) 132is connected electrically to the heating element power supply. The highlimit switch 132 causes the power to the heating element 124 to switchoff, when, for example, the temperature of the water in the rear header126 is higher than a set temperature. In some examples, the high limitswitch cut off temperature is set at 130° F.

The elbow 134 connects the heated water from the rear header 126 to theconduit 128. The heated water thermostat 130 measures the temperature ofheated pool water at the rear header 126 and the water thermostat 130opens to allow the heated water to flow to the conduit 128 when thewater reaches a set temperature. The conduit 128 is in fluidcommunication with heat exchanger bypass 114. In some examples, thewater thermostat 130 opens when the water is at 125° F.

In operation, pool water flows into the pool water inlet 110 of theelectric heater 100. The pool water thermistor 116 that is coupled tothe pool water inlet 110 measures the temperature of the incoming poolwater. A desired pool water temperature is set by a user at a controlpanel 410 (FIG. 4) that may be mounted to an external housing 142 of theelectric pool heater 100. The electric pool heater 100 helps to maintainthe pool water temperature at a temperature range close to the desiredtemperature. For example, if the user sets the desired pool water to 75°F., the pool heater can aim to maintain the pool temperature between74-76° F. When pool water flows into the pool water inlet 110, most ofthe incoming pool water flows to the heat exchanger 122. A small portionof the incoming pool water pushes up against the spring loaded heatexchanger bypass 114 and returns to the pool through the pool wateroutlet 112. When the pool water thermistor 116 measures the incomingpool water temperature, and the measured temperature of the water iswithin the temperature range of the desired pool water temperature, theheating element does not switch on. The incoming pool water fills up theplurality of metal pipes of the heat exchanger 122, and the waterthermostat 130 remains closed. As flow of pool water into the pool waterinlet 110 continues, the incoming pool water pushes up against thespring loaded bypass valve 114. The pool water then flows up through thebypass valve 114 to the pool water outlet 112 and back to the pool. Poolwater continues flowing into the pool water inlet 110 and through theheat exchanger bypass valve 114 to the pool water outlet 112 until thepool water thermistor 116 detects that the temperature of the incomingpool water is less than the set desired temperature.

When the pool water thermistor 116 detects that the incoming pool wateris below the set temperature, the electric heater 100 powers on when allthe safety devices are satisfied. If all the safety devices are notsatisfied, the electric element is not powered on. The flow switch 118and the high limit switch(es) 132, for example, act as safety devices.The flow switch 118 monitors the flow into the electric heater 100. Whenthe flow switch 118 determines that the flow is below a set flow value,the flow switch safety check is not satisfied. For example, when thefilter pump to the pool is off, the flow switch safety check is notsatisfied. The user may be notified that the flow switch safety check isnot satisfied at the control panel 410 (FIG. 4). In some examples, alight emitting diode (LED) at the control panel 410 (FIG. 4) may lightred if the flow switch safety is not met. The high limit switch(es) 132also act as a safety device. The high limit switch(es) 132 shut off thepower to the heating element if the water that exits the plurality ofheating tubes in the heat exchanger is at a temperature higher than aset temperature. In one implementation, the set temperature is 135° F.

If all of the safety devices are satisfied, then the electric heatingelement 124 is switched on. The electric heating element 124 begins toheat up the enclosure 136. The temperature of the enclosure 136 isincreased to a set temperature. For example, the enclosure is heated to200° F. In a preferred implementation, the inner wall of the enclosure136 is lined with one or more layers of insulation 146. The temperatureof the enclosure 136 is measured by the heat box thermistor 138, and ismaintained at the set temperature. Although not illustrated in FIG. 1,an element relay is used to cycle the heating element 124 on and off tomaintain the temperature of the enclosure 136 at the set temperature. Asdescribed earlier, the heat exchanger 122 is disposed within theenclosure 136, and includes a plurality of metal pipes or tubes. As theheating element 124 heats up the enclosure 136, the pool water in theplurality of metal pipes of the heat exchanger 122 is also heated. Heatfrom the electric heater 124 is transferred to the pool water in theplurality of metal pipes of the heat exchanger 122. In some examples,each of the plurality of metal pipes is a finned tubed copper pipe. Therate of heat exchange in the heat exchanger 122 is high due to thenumber of metal pipes and the diameter of each pipe. In some examples,the diameter of each of the plurality of metal pipes in the heatexchanger 122 is less than an inch and the heat exchanger comprises morethan 20 metal pipes. In these examples, each metal pipe contains a smallvolume of pool water that can be heated up faster than a tube with alarger diameter that holds a larger volume of water. A plurality ofmetal pipes in the heat exchanger 122 allows more heat to be absorbed bythe pool water in the pipes at a lower enclosure temperature.

As mentioned above, the heated water thermostat 130 is coupled to therear header 126. The heated water thermostat 130 measures thetemperature of the heated water that exits the heat exchanger 122. Whenthe temperature of the heated water reaches a set temperature, heatedwater thermostat 130 opens to allow the water in the heat exchanger 122to flow into the elbow 134 and into the conduit 128. The high limitswitch(es) 132 act a safety device, for example, by shutting off powerto the heating element 124 if the heated water exceeds a settemperature. In some examples, the high limit switch(es) 132 shut offthe power to the heating element 124 when the temperature of the heatedwater exceeds 135° F. As the water thermostat 130 opens to allow theheated water to flow to the conduit 128, pool water that enters theheater 100 through the pool water inlet 110 flows in to fill theplurality of metal pipes of the heat exchanger 122. At the same time,the heated water thermostat 130 may detect that the water in the heatexchanger 122 might drop below a set temperature and closes. While thisis occurring, the heated water in the conduit 128 flows through theconduit piping towards open valve 140. In some examples, the conduit 128is an insulated pipe that transports heated water to the pool wateroutlet 112. Simultaneously, a portion of the incoming pool water pressesagainst the bottom of the spring loaded bypass 114 and flow up towardsthe pool water outlet 112. The incoming pool water intermixes with theheater water from the conduit 128 before flowing back to the pool.

The process of heating water in the heat exchanger 122, as describedabove, is repeated until the pool temperature thermistor 116 determinesthat the incoming pool water at the pool water inlet 110 is within therange of the set temperature. The flow of pool water through the heater100 is continuous, if the pool water is above the set temperature and nofurther heating of the water is required, the incoming pool water ispassed through the bypass valve 114 and flows back through the poolwater outlet 112.

Referring to FIG. 2, and as discussed above, the electric pool heater100 includes a pool water inlet 110 that is connected by pipe unions 144to a pipe 110(a). Pipe 110(a) transports pool water to the heater 100.In some implementations, the electric pool heater 100 may be located ashort distance from the pumping system of the pool. The flow switch 118is mounted to the inlet 110 and monitors the flow of pool water into thepool water inlet. When the flow switch determines that the flow in thepool water inlet is below a set flow value, the flow switch safety checkis not satisfied. For example, when the filter pump to the pool is off,the flow switch safety check is not satisfied. The pool water outlet 112is connected to pipe 112(a) by pipe unions 144. Pipe 112(a) is in fluidcommunication with the pool. In some examples, pipes 110(a) and 112(a)are PVC pipes.

As discussed above, the heater 100 can include an enclosure 136, whichsurrounds either partially, or wholly, the heat exchanger 122, theheating element 124 and a condensation pan 125. In one implementation,the enclosure 136 is an insulated enclosure. For example, the enclosureis a metal, such as aluminum or stainless steel, box that is surroundedby one or more layers of insulating material 146. In some examples, theenclosure is a 2 feet by 2 feet square box. In some implementations, theenclosure can be formed of two complementary parts coupled together. Asdescribed with respect to FIG. 1, opening a top part of the two partenclosure 136 exposes the plurality of metal pipes of the heatexchanger, as well as the electric heater element 124. The heat boxthermistor 138 is mounted to the inner wall of the enclosure 136. Thethermistor 138 measures the temperature within the enclosure 136. Thecondensation pan 125 is located at the base of the enclosure 136. Thecondensation pan 125 extends the length, or a portion thereof, of theplurality of metal pipes of the heat exchanger 122. The condensation pan125 collects any excess moisture that may be produced as the heatexchanger heats the pool water. In some examples, the condensation pan125 is connected to a hose (not illustrated) that flows out to theground beneath the heater. In other examples, the condensation pan 125is a pan that can be removed by a user and emptied.

FIG. 3 illustrates the side view of the front header 120 of the electricheater 100. In this example, the enclosure 136 is formed of two partsthat are coupled together. The enclosure 136 is an insulated enclosurewith a top part of the enclosure 136(a) and a bottom part of theenclosure 136(b) coupled together. In some examples, the enclosure 136can be a metal box such as an aluminum box. The walls of the enclosurecan be lined with one or more layers of insulation 146. The two parts ofthe enclosure 136 can be coupled together using a plurality of fastenermechanisms (not shown). For example, glue tabs and rivets can be used,either individually or in combination, to fasten the two complimentaryparts of the enclosure 136 together. In other implementations, screws,bolts, or other fasteners may be used in conjunction with adhesivematerials, but adhesives are not required. The top part of the enclosure136(a) can be removed to expose the plurality of metal pipes within theheat exchanger 122. In some examples the heat box thermistor 138 ismounted to the inner wall of the bottom part of the enclosure 136(b). Inother examples, the thermistor can be mounted to any section of theinner wall of the enclosure 136. The heat box thermistor 138 measuresthe internal temperature of the enclosure 136.

FIG. 4 is a side view of an external housing unit 400 for the electricheater 100. As mentioned earlier, the electric pool heater 100 can becontained within a housing unit. FIG. 4 is the view of the housing unit400 from the side of the electric heater 100 with the pool water inlet110 and pool water outlet 112. In the example illustrated in FIG. 4, thehousing unit 400 can be formed of two complimentary halves, a topsection 420 and a bottom section 430. In some examples the housing unit400 can be an insulated housing unit. For example, the inner walls ofthe top section 420 and bottom section 430 of the housing unit 400 canbe lined with one or more layers of insulation. In other examples, thehousing unit 400 is not insulated. The housing unit 400 may be formed ofa metal, for example aluminum. The bottom section 430 of the housingunit can be formed in a pentagonal shape. As illustrated the bottomsection 430 can have sloped corners 440. In addition, the top section420 can include sloped sections to allow, for example, rain water to runoff the housing unit 400 as opposed to collecting on the top of the unit400. The housing unit 440 can be mounted on or include one or more legsections 450.

The housing unit 400 can include a side panel 460 that can have acircular cut out for each of the pool water inlet 110 and the pool wateroutlet 112. In some examples, the side panel 460 can be removable. Thetop section 420 of the housing unit can have a raised sloped corner toaccommodate the conduit 128 of the electric heater than transportsheated water to the pool water outlet 112. In some examples, the topsection 420 of the housing unit is removable. The user control panel 410can be mounted to the top section 420 of the housing unit 400. Thecontrol panel 410 can include a power switch, a temperature control, anda mode control. In some examples, the control panel 410 can include adigital display that displays the temperature selected by the user. Thecontrol panel 410 can also display the current pool temperature. In someimplementations, the control panel 410 can include an LED thatrepresents each safety device. For example, if the flow switch detectsthat the flow is lower than a selected flow value, the LED thatrepresents the flow switch at the control panel can light up redalerting the user of low flow.

A number of implementations and alternatives have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the disclosure. Forexample, while the illustrated examples and descriptions refer to anelectric pool water heater, the heater described herein may be appliedto other sources of water, including drinking water. In addition, theheater described herein may find application in certain industrial ormanufacturing scenarios as well. Accordingly, other implementations arewithin the scope of the following claims.

1. An electric heater for heating pool water comprising: an enclosure; apool water inlet and outlet; a heat exchanger disposed within theenclosure and comprising a plurality of metal pipes coupled to the poolwater inlet and outlet; an electric heating element disposed within theenclosure and spaced apart from the plurality of metal pipes; and aconduit coupled between the plurality of metal pipes and the pool wateroutlet.
 2. The electric heater of claim 1 wherein the heat exchangercomprises 20 to 25 metal pipes.
 3. The electric heater of claim 1wherein each of the plurality of metal pipes comprises copper.
 4. Theelectric heater of claim 1 further comprising: a thermal sensor tomeasure the internal temperature of the enclosure.
 5. The electricheater of claim 1 wherein the enclosure comprises a first insulatedportion coupled to a second is insulated portion.
 6. The electric heaterof claim 1 further comprising: a first header and a second header,wherein the first header is in fluid flow communication with the poolwater inlet and a first end of each of the plurality of metal pipes, andwherein the second header is in fluid flow communication with a secondend of each of the plurality of metal pipes and the conduit.
 7. Theelectric heater of claim 6 wherein a temperature-dependent flowthermostat is coupled between the second header and the conduit and isin fluid flow communication with the second end of each of the pluralityof metal pipes and the conduit.
 8. The electric heater of claim 7wherein the temperature-dependent flow thermostat is set to permit flowof heated pool water to the pool when the pool water heated by theexchanger reaches a temperature of about 125° F.
 9. The electric heaterof claim 1 wherein the pool water inlet and the pool water outlet are influid flow communication with a bypass valve.
 10. The electric heater ofclaim 1 wherein each of the plurality of metal pipes is the same lengthand is evenly spaced from each other.
 11. The electric heater of claim 1wherein each of the plurality of metal pipes has a diameter of about 0.5to about 1 inch.
 12. The electric heater of claim 1 further comprising acondensation pan disposed within the enclosure.
 13. A method for heatingpool water comprising: receiving pool water through an inlet of anelectric pool water heater; flowing a portion of the pool water througha plurality of metal pipes spaced apart from an electric heatingelement; intermixing the portion of the pool water that has flowedthrough the plurality of metal pipes with a portion of the pool waterflowing through a bypass valve; and flowing the intermixed portions ofpool water through an outlet of the electric pool water heater to thepool.
 14. The method of claim 13 wherein the portion of the pool waterthat flows through the plurality of metal pipes is heated to a settemperature.
 15. The method of claim 14 wherein the pool water thatflows through the plurality of metal pipes is heated to 125° F.
 16. Themethod of claim 14 wherein a temperature dependent flow thermostat isopened to allow the portion of the water that is flowed through theplurality of metal pipes to intermix with the portion of water thatflows through the bypass valve when the water in the plurality of metalpipes is at the set temperature.
 17. The method of claim 13 whereinflowing a portion of the pool water through a plurality of metal pipescomprises: receiving, by a first header, a portion of the pool waterfrom the inlet; and distributing, by the first header, the portion ofthe pool water to a first end of each of the plurality of metal pipes.18. The method of claim 17 wherein the portion of pool water from theinlet that is received by the first header is below a set temperature.19. The method of claim 18 wherein the plurality of metal pipescomprises 20 to 25 pipes and the pipes comprise a diameter of about 0.5to about 1 inch.